The aims of this study were (i) to describe the relative intensity of simulated tennis play based
on the cumulative time spent in three metabolic intensity zones, and (ii) to determine the relationships
between this play intensity distribution and the aerobic fitness of a group of competitive
players. 20 male players of advanced to elite level (ITN) performed an incremental oncourt
specific endurance tennis test to exhaustion to determine maximal oxygen uptake
(VO2max) and the first and second ventilatory thresholds (VT1, VT2). Ventilatory and gas
exchange parameters were monitored using a telemetric portable gas analyser (K4 b2,
Cosmed, Rome, Italy). Two weeks later the participants played a simulated tennis set against
an opponent of similar level. Intensity zones (1: low, 2: moderate, and 3: high) were delimited
by the individual VO2 values corresponding to VT1 and VT2, and expressed as percentage of
maximum VO2 and heart rate. When expressed relative to VO2max, percentage of playing
time in zone 1 (77 ± 25%) was significantly higher (p < 0.001) than in zone 2 (20 ± 21%) and
zone 3 (3 ± 5%). Moderate to high positive correlations were found between VT1, VT2 and
VO2max, and the percentage of playing time spent in zone 1 (r = 0.68–0.75), as well as low to
high inverse correlations between the metabolic variables and the percentage of time spent
in zone 2 and 3 (r = -0.49–0.75). Players with better aerobic fitness play at relatively lower
intensities. We conclude that players spent more than 75%of the time in their low-intensity
zone, with less than 25%of the time spent at moderate to high intensities. Aerobic fitness
appears to determine the metabolic intensity that players can sustain throughout the game.